1. Technical Field
The present invention relates to a catheter, and particularly relates to a catheter configured to be inserted into a blood vessel for use.
2. Description of the Related Art
Recently, percutaneous transluminal coronary angioplasty (PTCA) has been performed to treat a stenosis in a coronary artery. In PTCA, by using the Seldinger technique or the like, a guidewire for a guiding catheter is inserted into an arterial vessel, and along the guidewire, a guiding catheter is introduced into the arterial vessel. Then, with the guidewire preceding the guiding catheter, the tip of the catheter is positioned at the entrance to a coronary artery. Next, only the guidewire is taken out and a thinner guidewire for a balloon catheter is inserted into the guiding catheter to allow the tip thereof to reach a position beyond a stenotic site. After that, a proximal end of the guidewire is inserted into a lumen of a balloon catheter from a distal end side thereof, and the balloon catheter is advanced along the guidewire until a balloon in a deflated state is positioned at the stenotic site. Then, the balloon is inflated to expand the stenotic site, restoring blood flow on the distal end side farther than the stenotic site.
In this way, the guiding catheter serves to introduce a guidewire for a balloon catheter and a balloon catheter to a coronary artery entrance. The tip of the guiding catheter needs to be engaged at the coronary artery entrance. However, upon insertion of the guidewire and the balloon catheter into the coronary artery, a counterforce acts on the guiding catheter, which may cause the guiding catheter to be displaced from the coronary artery entrance. Thus, there has been known a method for maintaining the tip position of a guiding catheter at a coronary artery entrance (for example, see: Japanese Patent Application Laid-Open Publication No. 2006-230442). In this method, a shaft of the guiding catheter is made of a relatively hard resin and curved into shape, and the curved portion of the catheter is pressed against the inner surface of the blood vessel to push itself thereagainst.
However, even with the structure of pushing against the inner surface of the vessel by the curved portion, it is difficult to prevent completely the displacement of the tip position of the guiding catheter from the coronary artery entrance.